Devices having a leading penetrating end used to penetrate a substance are used in many types of applications, including use in archery equipment and surgical instruments. A popular type of penetrating end point or tip that is used both in archery and surgery is the trocar tip. The word trocar has Latin roots of tres meaning three and carre meaning side of a sword or knife. A trocar tip is therefore three sided and is the pointed leading end of an object used to cut or pierce. The three sides of trocar tips are generally hollow ground. The term hollow ground refers to the grinding process used to fabricate the sides of the tip and generally means that the sides are dished-out or substantially concave, as compared to being flat. The hollow ground feature gives the tip better defined cutting edges at the juncture of the sides with each other than the cutting edges at side junctures of tips having flat sides. The hollow ground feature also gives the tip the ability to easily push the substance being penetrated away from the tip. The earliest known use of trocar tips date back to the medieval times where they were used on the leading ends of knights' lances.
In surgery a surgical trocar is one type of a surgical instrument that has a leading penetrating end. Surgical trocars are generally used to pierce body cavities during the surgical procedures of dropsy, endoscopy and laparoscopy etc. The penetrating ends of surgical trocars generally have a type of trocar tip, since from such tip they were named. There are various types of surgical trocars, with a variety of different options and accessories available depending on the procedure(s) to be performed. However, the leading end point of the surgical trocar should be as sharp as possible, should push penetrated or cut tissue away from its cutting path, and also should be as cost effective to produce as possible.
In archery a bow is used to shoot an arrow towards a target. A conventional arrow has a shaft, a nock at one end that receives the bow string, and an arrowhead or point that attaches to the opposite end of the arrow shaft which aids in penetrating the target. Arrowheads generally have a pointed forward end, and an opposite threaded shaft end that attaches the arrowhead to the arrow shaft. Arrowheads come in a variety of different sizes and configurations depending on their intended use. For example, there are specifically designed arrowheads for competitive target shooting, shooting fish, hunting birds or small game animals, and for hunting big game animals.
Arrowheads used for bowhunting are generally know as broadheads. Broadheads have cutting blades and kill game animals by cutting vital organs such as the lungs and vascular vessels such as arteries, which causes rapid hemorrhaging and/or suffocation. Quick and humane kills are dependent on accurate shot placement, and upon the amount or volume of the animal tissue that is cut. Hunting arrowheads that cut more tissue are more lethal, and therefore are better. The volume of tissue that is cut is determined by the cutting diameter of the arrowhead, the number of blades it contains, and by the distance the arrowhead penetrates into the animal. The two most common types of arrowheads used for hunting are fixed-blade arrowheads and blade-opening arrowheads or mechanical arrowheads. Blade-opening arrowheads differ from conventional fixed-blade arrowheads in that the cutting blades are folded up or held adjacent to the arrowhead body in a retracted position while the arrow is in flight, but at impact with the game animal rotate or pivot into an open position, whereas the blades of fixed-blade arrowheads are permanently held at a full cutting diameter position at all times.
Both blade-opening and fixed-blade arrowheads have a pointed tip end used for penetrating the game animal. The tip of the arrowhead may be separably attachable to the arrowhead body or may be integral with it. Conventional arrowheads have historically had two basic types of pointed arrowhead tips: bone-crushing chisel type tips such as the hollow ground trocar tip, and razor blade type tips. The razor blade tips are generally just an extension of the cutting blades of the arrowhead and terminate in a leading pointed apex. Both types of arrowhead tips are designed to maximize penetration and therefore provide a more lethal arrowhead by cutting a larger volume of animal tissue. Despite their designs and intent both the bone crushing chisel tips and the razor blade tips fall short of providing optimum penetrating performance. Since the arrowhead razor blade type tips generally have a true cutting edge, or a cutting edge that has a small enough angle between opposing sides so as to make it as sharp as a razor or scalpel blade, they penetrate the best through soft tissues such as skin, muscles, lungs and other internal organs by slicing or cutting. But when a razor blade tip impacts bone the thin cutting blade generally gets sheared or broken-off due to the heavy impact forces delivered to it, and thus leaves a blunt snagging leading end that greatly inhibits penetration and therefore is less lethal in many instances--since arrowheads very commonly impact bone when penetrating game animals. The bone-crushing chisel tips on the other hand split right through heavy bone but lack a truly sharp cutting edge and therefore do not perform as well in penetrating the skin and other soft tissues.
Attempts in the prior art have been made to combine a scalpel sharp cutting edge with bone splitting capabilities into an optimally penetrating arrowhead tip, but these attempts have their own problems as well. For example the introduction of chisel tips with hollow ground sides, such as the three sided trocar tip for arrowhead points helped reduce the angle of the cutting edge between the sides of the tip. But the edges of conventional trocar arrowhead tips and other hollow ground arrowhead tips are still relatively dull and are a far cry from having the fine cutting angle or edge a scalpel or razor blade possesses. Other attempts in the prior art to increase the sharpness of the edges of chisel type arrowhead tips have been made by increasing the curvature of the hollow ground sides. This practice greatly weakens the tip giving it problems similar to those of the razor blade type tips and also provides a tip that does not push the tissue away from the arrowhead optimally.
It is apparent that there are needed improvements in cutting tips.
It is apparent that there is a need for an arrowhead cutting tip that combines the optimal penetration features of the most rugged bone splitting trocar or chisel type arrowhead tips with the razor sharp cutting features of the razor blade type arrowhead tips into one arrowhead tip.
It is also apparent that there is a need for a cutting tip of a surgical trocar that is cost effective to produce, extremely sharp, and that pushes the penetrated or cut tissue away from its cutting path.